The present invention relates generally to a multiple-wavelength laser. More specifically, the present invention relates to a multiple-wavelength mode-locked laser that can be used in wavelength-division multiplexing (WDM) communications.
A known multiple-wavelength laser has a gain medium that produces multiple wavelengths corresponding to multiple longitudinal modes of the laser's resonance cavity. See Four-wavelength, 10-GHZ picosecond pulse generation from an active mode-locked single-stripe diode laser, H. Shi, G. A. Alphonse, J. C. Connolly, P. J. Delfyett, Cleo '97, p. 86, May 20, 1997. This multiple-wavelength laser includes a grating and spatial filter arrangement within the resonance cavity. The grating and spatial filter arrangement angularly separates the wavelength components produced by the gain medium and eliminates some of these wavelength components by absorption of the spatial filter. This laser also diverts a portion of the light from the grating to perform diagnostics on the laser light.
This multiple-wavelength laser, however, requires a large number of components that affect the compactness and durability of the laser. In addition, wavelength stabilization is not easily performed by the above-described laser and single-transverse-mode operation can result in some loss of output power.